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High turnover osteoporosis in acro-osteolysis (Hajdu-Cheney syndrome)
V Nunziata1, G di Giovanni, P Ballanti
1Istituto di Medicina Interna e Malattie Metaboliche, Università di Napoli, Italy.
Insights
Hajdu-Cheney syndrome causes bone loss through increased osteoclastic resorption, not reduced formation. This study confirms active bone resorption drives both distal osteolysis and generalized osteoporosis in this rare condition.
Area of Science:
- Bone biology and metabolic disorders
- Genetics and rare diseases
Background:
- Hajdu-Cheney syndrome is characterized by acro-osteolysis and diffuse osteoporosis.
- Previous theories suggested reduced bone formation as the primary mechanism for osteoporosis in this syndrome.
Observation:
- A patient with sporadic Hajdu-Cheney syndrome underwent bone histology, calcium kinetics, and hormonal analysis.
- Bone biopsy revealed severe osteoporosis with increased osteoclastic resorption and decreased bone formation.
Findings:
- Total body calcium clearance was significantly elevated, confirming active osteoclastic bone resorption.
- Serum levels of parathormone, 1,25-dihydroxycholecalciferol, alkaline phosphatase, and urinary hydroxyproline were within normal ranges.
Implications:
- The findings suggest that active osteoclastic bone resorption is the primary mechanism underlying both generalized osteoporosis and distal osteolysis in Hajdu-Cheney syndrome.
- This mechanism may be driven by local factors that stimulate osteoclastic activity.
Abstract:
Acro-osteolysis with diffuse osteoporosis in the absence of other associated diseases is named Hajdu-Cheney syndrome. Reduced bone formation rather than enhanced bone resorption has been indicated as the mechanism of osteoporosis. On the assumption that in this syndrome the active bone resorption which produces distal osteolysis must also predominate in generalized osteoporosis, we investigated bone histology, calcium kinetics, calciotropic hormones and bone markers in a patient suffering from sporadic Hajdu-Cheney syndrome. A radius bone biopsy taken far from the osteolytic lesions showed severe osteoporosis with a marked increase in osteoclastic bone resorption and reduced bone formation. Total body calcium clearance, performed through an analysis of the kinetics of calcium infusion, was 2.8 times higher than in normal controls, indicating the presence of active osteoclastic bone resorption. Serum parathormone, 1,25-dihydroxycholecalciferol, alkaline phosphatase and urinary hydroxiproline were in the normal range. These data indicate that in Hajdu-Cheney syndrome trabecular osteoporosis is produced by the same mechanism that induces distal osteolysis, which suggests that it may be sustained by local acting factors stimulating osteoclastic resorption.